This CL attempts to fix a chrome crash seen in the wild. Without a
reproducer, the current working theory is that we hit a 'null' context
in some edge case, causing us to access an empty handle. This CL
prevents the empty context handle to be dereferenced.

TBR=yangguo@chromium.org

Bug: chromium:1038747
Change-Id: Icd6f4853a22ddbf1e504f0f0f90c065b3437f8ab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2000752Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65776}